Preference of grazing goats for cool-season annual clovers

 

 

T.H. Terrill^{I, #}; W.F. Whitehead^I; G. Durham^II; C.S. Hoveland^II; B.P. Singh^I; S. Gelaye^I

^IFort Valley State University, Fort Valley, GA 31030, USA
^IIThe University of Georgia, Athens, GA 30602, USA

 

 

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ABSTRACT

Information on improved forages for goat grazing is lacking for the southern USA. Two cafeteria-style grazing trials were completed to determine preference of meat-type goats for cool-season annual clovers in Georgia. In both experiments, 8 replicates of 6 plots of clover cultivars were established, individually fenced, and grazed by Spanish goats for 48 hours during two grazing periods. Forage preference was determined by weighing strips of forage cut from plots pre- and post-grazing (Experiment 1) and by ocular scoring (1 = no grazing to 10 = completely grazed) after 4, 24 and 48 hours grazing (Experiment 2). In Experiment 1, 'Dixie' and 'AU Robin' crimson clover (Trifolium incarnatum L.) were most preferred, 'AU Sunrise' crimson clover and 'Yuchi' arrowleaf clover (Trifolium vesiculosum Savi) were intermediate, and 'Segrest' ball clover (Trifolium nigrescens Viv.) and 'R18' rose clover (Trifolium hirtum All.) were least preferred. Forage preference was not influenced by dry matter yield, fibre content or protein concentration. In Experiment 2, Dixie and AU Sunrise crimson clover were most preferred in the first cutting, 3 arrowleaf clover types and 'Americus' hairy vetch (Vicia villosa Roth) were intermediate and R18 rose clover was least preferred. When the crimson clover plots were not available for the second grazing period, the goats most preferred Yuchi arrowleaf clover, with 'BYMV' arrowleaf clover and hairy vetch intermediate, and rose clover least preferred. Crimson clover appears to be a useful forage for winter-spring grazing of goats in the southern USA.

Keywords: Grazing preference, goats, clover

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stratified by weight and randomly assigned to the remaining 8 blocks, and grazing was initiated. In Experiment 1, a 0.76 m x 3.05 m strip of forage was cut out of the middle of each plot pre- and post-grazing, weighed fresh and subsampled for determination of dry matter (DM) yield, quality components, and calculation of total forage DM consumed from each plot. Forage subsamples were dried at 50 °C for 48 hours, ground to 1 mm particle size, and analyzed for crude protein (CP) (AOAC, 1990), neutral detergent fibre (NDF) and acid detergent fibre (ADF) (Goering & Van Soest, 1970). For Experiment 2, all plots were visually evaluated to determine extent of pasture use after 4 hours, 24 hours and 48 hours grazing. Two observers assigned each plot an ocular preference score (Shewmaker et al., 1997) from 1 (no grazing) to 10 (completely grazed).

Preference (DM consumed) and forage quality data for Experiment 1 were analyzed as a randomized block, while preference data from Experiment 2 (ocular preference score after 4, 24, and 48 hours grazing) were analyzed as a randomized block with repeated measures analysis using a GLM procedure (SAS, 1992).

 

Results

In Experiment 1, forage availability at the initial grazing was highest for AU Robin crimson, R18 rose, and Dixie crimson clovers, intermediate for Yuchi arrowleaf, and lowest for AU Sunrise crimson and Segrest ball clover (1137, 1023, 982, 491, 298, and 255 kg/ha, respectively). For the second grazing period, forage availability ranged from 838 to 446 kg/ha, with highest to lowest ranking for arrowleaf, ball, rose, Dixie crimson, AU Robin crimson, and AU Sunrise crimson clover, respectively. Crude protein and fibre concentrations also differed (P < 0.05) among the clover cultivars, with the cultivars ranking differently during each grazing period. During the initial grazing, forage CP, NDF, and ADF ranged from 24.2 to 18.5, 32.2 to 25.3, and 21.1 to 17.6%, respectively, while these constituents ranged from 23.4 to 18.2, 42.8 to 26.6, and 30.3 to 17.4%, respectively, in the second grazing period.

Despite differences in forage availability and quality indices in each grazing period, there was no effect of cutting date on DM consumed for the different clover cultivars, so data from the two grazing periods in experiment 1 were pooled. Total DM consumed by the goats averaged 372, 368, 322, 218, 145, and 100 g for Au Robin crimson, Dixie crimson, AU Sunrise crimson, arrowleaf, rose, and ball clovers, respectively.

Consumption of Dixie and AU Robin crimson clover was significantly higher than for ball (P < 0.05) or rose (P < 0.07) clover.

In the initial grazing period in Experiment 2, yearling kids also preferred (P < 0.05) the crimson clover cultivars over the arrowleaf clover types and hairy vetch, with rose clover least preferred (Table 1). With no crimson clover available during the second grazing period, the kids preferred Yuchi arrowleaf clover without fungicide coating significantly (P < 0.05) more than BYMV arrowleaf, with rose clover preferred the least.

 

Discussion

Both mature and growing goats showed a preference for crimson clover over other clover types, and preference was not related to DM availability, CP or fibre in the different forages. Dixie crimson clover was lower in fibre and intermediate in CP concentration and DM yield, but was most preferred by the goats. Shewmaker et al. (1997) reported little relationship between DM yield and preference of grazing beef cattle for different cultivars of endophyte-free tall fescue (Festuca arundinacea Schreb.). These authors also reported higher repeatability and time savings for an ocular scoring technique compared with cutting before and after grazing to establish forage preferences of grazing animals. We confirmed these results in the current study. The coefficient of variation (CV) for the ocular preference scoring technique used in the second experiment averaged 34%, while the CV for cutting before and after grazing to establish preference (Experiment 1) was 49%. Although no direct comparison of the two techniques was done in the current investigation, the ocular preference scoring technique was much easier and appears to be an effective means of establishing grazing preference of goats.

 

Conclusions

Crimson clover was preferred by goats over other clover types and may be suitable as high-quality winter-spring pasture for goat production in the southern USA. Although less preferred than crimson, arrowleaf clover has a longer grazing season in this region and may also have potential for goat grazing. Further research is needed with these species to determine performance of goats grazing annual clover as a component of the diet.

 

References

AOAC, 1990. Official methods of analysis (25th ed.). Association of Official Analytical Chemists, Inc. Arlington, VA, USA.         [ Links ]

Clark, D.A., Lambert, M.G., Rolston, M.P. & Dymock, N., 1982. Diet selection by goats and sheep on hill country. Proc. N. Z. Soc. Anim. Prod. 42, 155-157.         [ Links ]

Goering, H.K., & Van Soest, P.J., 1970. Forage fiber analyses (apparatus, reagents, procedures, and some applications). Agric. Handb. 379, U.S. Gov. Print. Office, Washington D.C., USA.         [ Links ]

SAS, 1992. Statistical Analysis Systems user's guide (Version 6.07). SAS Institute Inc., Carey, North Carolina, USA.         [ Links ]

Shewmaker, G.E., Mayland, H.F. & Hansen, S.B., 1997. Cattle grazing preference among eight endophyte-free tall fescue cultivars. Agron. J. 89, 695-701.         [ Links ]

Stevens, D.R., Casey, M.J., Baxter, G.S. & Miller, K.B., 1993. A response of angora-type goats to increases of legume and chicory content in mixed pastures. Proc. XVII Int. Grassl. Cong. pp. 1300-1301.         [ Links ]

 

 

# Corresponding author. Email: terrillt@fvsu.edu